Trench drain conduits of polymer concrete have found many uses where high strength and durability justify the increased cost over tile, concrete and other ceramic materials. Such drains are typically channel-shaped trench drains, open at the top, and recessed into a surface, such as a floor, to catch liquid run-off from spills or leaks. However, where the liquid that may spill or leak or otherwise require collection is environmentally unsafe, such as hazardous chemical liquids, the Environmental Protective Agency of the U.S. Government has required secondary containment in addition to the primary container to inhibit any such liquid from escaping into the environment.
A previous chemically safe trench drain that provides secondary containment utilizes a double-walled trench drain disclosed in U.S. Pat. No. 4,940,359. That trench drain is formed of two initially separate channel members pre-assembled, one within the other, of convenient modular length for shipment, assembly and use, and that can conveniently be joined, one to the next, in a sealed relationship during installation. The inner and outer channel members are formed of cast polymer concrete, i.e., a resin and a refractory filler.
This previous double-channeled trench system is relatively expensive and in many cases is sturdier than necessary. In addition, to assure flow within the trench system, it and the floor in which it is installed must slope from one end of the trench toward a drain, which can be disadvantageous.